This invention relates to improvements in the attachment of the friction material in a clutch brake assembly.
Manual transmissions are used on many different types of vehicles and in particular trucks and other heavy vehicles. Manual transmissions typically include an input shaft and a clutch to selectively engage the transmission input shaft with an output shaft from an engine.
When shifting into first gear, low, or reverse gears, in a manual transmission the rotation of the transmission shaft should be stopped before engagement with the engine output shaft. This ensures quick engagement of the gears without gear clash.
The manual transmissions utilized on passenger cars and light duty trucks are typically synchronized transmissions. The synchronized transmissions automatically stop the rotation of the transmission shaft before engagement with the engine.
The manual transmissions utilized on heavy duty trucks and other heavy vehicles are typically non-synchronized transmissions. Non-synchronized transmissions require a mechanism for stopping the rotation of the transmission shaft. One such mechanism is a clutch brake assembly which effectively stops the rotational speed of the shaft before engagement with the engine.
Clutch brake assemblies typically include a brake disc which is rotatably driven by the transmission shaft. The brake disc can slide along the shaft between a clutch release bearing and a surface of the transmission. Friction material is bonded to both sides of the brake disc.
During shifting, the clutch brake assembly is engaged by fully depressing a clutch pedal. This operation disengages the clutch and the transmission shaft from the engine. The clutch pedal is linked to an actuation fork which moves the release bearing along the shaft toward the brake disc. The release bearing then engages the brake disc and sandwiches the brake disc between the transmission surface and the release bearing to stop any rotation of the shaft. Typically, a bearing retainer is mounted to the transmission surface for engagement with the brake disc. This type of clutch brake assembly performs well in stopping the rotation of the transmission shaft.
After repeated use, the friction material on the brake disc wears and the brake disc must be replaced. Typically the transmission must be disconnected to remove and replace the brake disc. These known discs completely surround the shaft and thus require disconnection of the shaft. As appreciated by those skilled in the art, disconnecting a transmission from a heavy duty truck or any other heavy vehicle can be very expensive, time consuming, and labor intensive. One proposed attempt to remedy this problem suggests a two piece brake disc which can be removed and replaced without removing the transmission. This suggestion has not been adapted widely in the industry.
Another deficiency is that the brake disc wears excessively on the release bearing and the bearing retainer. Accordingly, these components must sometimes be replaced, which also requires the disconnection of the transmission.
Hence, there is a need for a clutch brake assembly which does not wear on the release bearing and/or the transmission surface. In addition, there remains a need for a clutch brake assembly which can be easily replaced without disconnecting the transmission.